This pathway has been produced by representatives from both primary and secondary care to support the management of dermatological conditions. These guidelines accompany the publication of new referral criteria from GHFT. The pathway is based on both PCDS guidance on the management of dermatological conditions, GHFT guidelines and the current CCG commissioning policies and supports the local guidance agreed by experts throughout the healthcare system.

Seborrhoeic Karatoses Care Pathway Overview

A seborrhoeic keratosis (Seb K) is an extremely common benign overgrowth of epidermal keratinocytes, and is of unknown aetiology.

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Red Flags

A sudden onset of multiple Seborrhoeic Keratosis may very rarely be part of a paraneoplastic syndrome – the sign of Leser-Trelat.

There is debate as to whether or not this is a paraneoplastic phenomenon (associated with adenocarcinoma of the stomach or colon) due to the high prevalence of multiple seborrhoeic keratosis in elderly populations, however, should lesions erupt in the presence of weight loss, GI symptoms, malignant acanthosis nigricans or other 'red flags' then patients should be referred urgently for further investigations

Presentation / Assessment

Age of presentation - most commonly present from the fourth decade onwards, but can present at any age after puberty.

Symptoms

Frequently asymptomatic

Occasionally itch

Part / all of the lesion may come away with minimal trauma and cause bleeding

Distribution

The trunk and face are commonly affected, but they can arise on almost any body site

It is not uncommon to find multiple lesions and some patients have very large numbers

The most common presentation is that of a thickened ‘acanthotic’ lesion, which has the following characteristics:

An irregular warty, rough surface

Greasy appearance

‘Stuck-on’ – the lesion sits on top of normal looking skin and gives the impression that it can be easily picked off

1-3 cm in diameter (some can be larger)

Thinner lesions also occur and most commonly arise on the cheeks and lower legs

A verrucous keratosis - is where a viral wart has started to grow within a seborrhoeic keratosis. These changes are apparent both clinically and histologically.

The Leser-Trélat sign - this is characterised by the abrupt appearance of multiple seborrhoeic keratoses that rapidly increase in their size and number. There is debate as to whether or not this is a paraneoplastic phenomenon (associated with adenocarcinoma of the stomach or colon) due to the high prevalence of multiple seborrhoeic keratosis in elderly populations, however, should lesions erupt in the presence of weight loss, GI symptoms, malignant acanthosis nigricans or other 'red flags' then patients should be referred urgently for further investigations

Seborrhoeic keratoses take on various appearances including:

Acanthotic SK have a thickened epidermis with milia-like cysts and comedo-like openings. Bloods vessels are fine, regular and hairpin in shape

Multiple fissures and ridges, which looks like the surface of the brain

Thinner lesions have less in the way of the structures described above. Their features include a 'moth-eaten' border and other structures that often overlap with those seen in solar lentigo. It is unclear whether some seborrhoeic keratoses originate from solar lentigo. Another explanation is that the two lesions are very common and so can co-exist, especially on sun-exposed areas. In general one would best distinguish between the two by terming a brown patch as a solar lentigo, whereas even a thin seborrhoeic keratoses is likely on close inspection to be slightly elevated

Other presentations include a frogspawn-like appearance and what is described as 'fat fingers'

The predominant vascular pattern is that of hairpin-like vessels surrounded by a milky halo

The diagnosis of seborrhoeic keratosis is often easy.

A stuck-on, well-demarcated warty-surfaced plaque

Often pits and crypts can be seen in the surface, which may resemble a chocolate chip muffin, or the surface of a brain

Dermatoscopy often shows a disordered structure in a seborrhoeic keratosis, as is also true for a skin cancer. There are diagnostic dermoscopic clues to seborrhoeic keratosis, such as a well-defined edge, multiple orange or brown clods (due to keratin in skin surface crevices, also known as comedo-like openings), white clods (also known as “milia-like cysts”), curved thick brown lines forming a brain-like or cerebriform pattern.

If doubt remains, a seborrhoeic keratosis may be shaved, punch biopsied or excised for histology.

Initial Primary Care Management

Most seborrhoeic keratosis are best left alone, and should only be treated if symptomatic.

An inflamed seborrheic keratosis may mimic a skin cancer. If there is diagnostic doubt then photographs (ideally including dermoscopy) should be sent via the Advice and Guidance Service for dermatology advice.

If you are reasonably sure it is just an inflamed seborrheic keratosis, it is reasonable to treat with mild potency topical steroid such as hydrocortisone 1% once a day for 2 weeks and review the patient, or the lesion could be removed in primary care. The lesion must always be sent for histology if it is inflamed.

If there is any diagnostic doubt at the 2 week review then the patient should be referred, ideally with a photograph via the Advice and Guidance Service. The clinician must be sure that the patient will attend for review, and must check they have done so.

An individual seborrhoeic keratosis can easily be removed in primary care if desired. Reasons for removal may be that it is unsightly, itchy, or catches on clothing.

Shave excision (or curettage) with haemostasis using electrocautery or aluminium chloride [Driclor] (a sample should always be sent for histology)

Cryotherapy (liquid nitrogen) for thinner lesions (repeated if necessary) [never use cryotherapy if there is any doubt about the diagnosis, as there is no sample for histology]

Ablative laser surgery (not generally available in primary care, but can be done in private sector)

All methods have disadvantages. Treatment-induced loss of pigmentation is a particular issue for dark skinned patients. Scarring is common after removal of seborrheic keratosis. There is no easy way to remove multiple lesions on a single occasion.

Reason for Pathway Selection

This pathway has been produced by representatives from both primary and secondary care to support the management of dermatological conditions. These guidelines accompany the publication of new referral criteria from GHFT. The pathway is based on both PCDS guidance on the management of dermatological conditions, GHFT guidelines and the current CCG commissioning policies and supports the local guidance agreed by experts throughout the healthcare system.